Integration of functional layers in or on transparent plastic parts for vehicle manufacture

ABSTRACT

The invention relates to a transparent plastic part ( 1, 11 ) of an electrically nonconductive material on or in which electrically conductive structures ( 2 ) are integrated for use in a motor vehicle, where according to the invention the electrically conductive structures ( 2 ) are printed on an outside surface.

The invention relates to the integration of functional layers, in particular electrically conductive structures such as antennas, heating elements, and photovoltaic elements, in or on transparent plastic parts used in automobile manufacture.

The use of transparent plastic parts is becoming more widespread in automobile manufacture. Compared to glass, transparent plastic parts have a number of advantages. The savings in weight is directly reflected in reduced fuel consumption. In addition, more favorable aerodynamic characteristics may be obtained due to the greater freedom in design resulting from diverse and virtually unlimited shapes in the injection-molding and injection-stamping processes, which also reduces energy consumption. Use of these plastics as side and rear windows or as roofs in automobiles, for example, lowers the vehicle's center of gravity, thereby positively influencing the stability of the vehicle.

An object of the invention is to provide a transparent plastic part made of an electrically nonconductive material, on or in which electrically conductive structures are integrated, and that is designed for use in a vehicle, by means of which the above-described disadvantages are avoided and/or by which the above-described advantages may be retained, and by means of which conductor structures for current conduction or signal transmission, as antennas, or for photovoltaic elements may be mounted.

This object is achieved by the features of claim 1.

Polycarbonate (PC) and polymethlymethacrylate (PMMA) are preferably used in window panes. Their characteristics are essentially comparable to glass. Polycarbonate does not shatter, and is impact-resistant, tintable, and dimensionally stable. When these materials are not scratch-resistant, this characteristic can be imparted by additionally applying-an anti-scratch coating (for example, using ceramic nanoparticles in a silicon layer). The possibility for working the plastic by drilling, sawing, milling, welding, and gluing, for example, represents further advantages compared to the conventional use of glass. The integration of additional functions such as antennas, antenna systems, heating elements, and photovoltaic elements, for example, desired by automobile manufacturers or customers promotes the use of transparent plastic as an alternative to glass, and is the object of the present invention.

According to the invention, the electrically conductive structures applied by means of a printing process are located on the exterior of the transparent plastic part. This has the advantage that the transparent plastic part can be manufactured and, if needed, finish-machined according to its intended use, so that by means of a printing process, in particular a screen-printing process, the electrically conductive structures can be subsequently mounted on the exterior of the transparent plastic part. In this manner the greatest possible freedom of design is maintained for manufacturing and shaping of both the transparent plastic part and the electrically conductive structures in order to achieve the desired function in the plastic part by means of the electrically conductive structures.

Illustrated embodiments of the invention, which do not limit the invention, are described in the dependent claims and are also illustrated in the figures and described below.

In the figures:

FIG. 1 shows the transparent plastic component directly imprinted;.

FIG. 2 shows the transparent plastic component directly imprinted. A protective film is then laminated thereon. This protective film may also be an applied silicon layer (anti-scratch coating);

FIG. 3 shows a transparent film imprinted and subsequently joined to the transparent component. The conductive structures may be imbedded. Two shapes are shown.

FIG. 4 shows a transparent film imprinted and then insert-molded with the transparent plastic. As illustrated, an additional protective layer may be applied.

FIG. 5 shows a transparent film imprinted and used for the insert molding process as a transfer medium that transfers the conductive structures into the transparent target component. A protective layer is possible as in FIG. 4.

FIG. 1 shows a detailed illustration of a transparent plastic part 1 having electrically conductive structures 2 printed thereon. The transparent plastic part 1 preferably is made of polycarbonate (PC) or polymethlymethacrylate (PMMA), the electrically conductive structures being applied by means of a printing process, preferably a screen-printing process. For printing, electrically conductive pastes are preferably used which may be formed into any desired shape for the electrically conductive structures 2. As equivalent alternatives to the printing process, other methods including but not limited to spraying, painting, ink jet, airbrush, or spattering are also possible.

FIG. 2 shows an illustrated embodiment in which a protective layer 3 is applied over the transparent plastic part 1 and the conductive structures 2, so that the electrically conductive structures 2 are imbedded. This protective layer 3 may be a protective film which is laminated, for example. Alternatively, the protective film could also be an applied silicon layer for protecting the conductive structures 2 from damage (in particular interruptions) and protecting the transparent plastic part 1 from scratches (anti-scratch layer).

FIG. 3 shows that a transparent film 4 is imprinted with the electrically conductive structures 2, and this film 4 is applied to the plastic part, in particular glued or laminated thereon. The upper part of FIG. 3 shows that the plastic film 4 is applied to the plastic part 1 at the surface opposite from the electrically conductive structures 2. The lower part of FIG. 3 shows the reverse situation in which the plastic film 4 is applied to the surface of the plastic part 1 at the side on which the conductive structures 2 have been printed. Thus, as a result of the additionally applied layer in the form of the film 4 the electrically conductive structures 2 are imbedded. The film 4 may be attached to the plastic part 1 over a part or most of its surface, in particular over the entire surface.

FIG. 4 shows that a transparent plastic part 7 is imprinted and is then oversprayed with a transparent plastic 6. The upper illustration of FIG. 4 shows that the electrically conductive structures are printed on the transparent plastic film 7 (alternatively, on the rigid transparent plastic part 1), and by use of an appropriate method (insert molding, for example), a transparent plastic is injection-molded or insert-molded to the plastic film 7 (or to the plastic part 1). According to the upper illustration of FIG. 4, it is particularly advantageous for the surface of the molded plastic 6 to be level with the surface of the electrically conductive structures in order to produce a flat surface. Alternatively or additionally, of course, the injection-molded plastic may be molded over the surfaces of the electrically conductive structures that project from the plastic film 7.

The lower illustration of FIG. 4 shows that both the injection-molded or insert-molded transparent plastic 6 and the electrically conductive structures 2 are enclosed by an additional protective layer 8, in particular an anti-scratch layer.

FIG. 5 shows that a transfer medium 9 has been provided before actually carrying out an injection molding process with the conductive structures 2, this premanufactured transfer medium 9 being attached to the transparent plastic part 1, or alternatively, to the transparent plastic film 7. During the injection molding process (insert molding process) the electrically conductive structures 2 are then transferred via a transfer film 10 to the target component, namely, a transparent plastic part 11 having conductive structures. The finished transparent plastic part 11 may also be provided with an additional coating, in particular the anti-scratch coating 3.

The plastic parts 1 and 11 shown in FIGS. 1 through 5 are used according to the invention for vehicular panes in applications such as window panes (windshield, rear or side windows) or in the vehicle roof (transparent and therefore light-permeable sliding roof).

The geometric dimensions of the electrically conductive structures 2, in particular their length, width, height, cross section, and longitudinal extension, are designed according to their function. Thus, the electrically conductive structures 2 may be antenna structures, for example, for receiving or transmitting high-frequency signals. For this purpose, in a diversity system, for example, multiple linear electrically conductive structures 2 are configured in parallel or at right angles on a vehicle window pane, but are separated by a minimum distance to prevent mutual interference of the reception and transmission characteristics. If the electrically conductive structures 2 are used for rear window heating, for example, it is possible for two electrically conductive structures 2 to be aligned perpendicular to the sides of the rear window, and for numerous additional, closely spaced electrically conductive structures 2 of extremely thin cross section to be provided therebetween, to prevent the optical characteristics of the transparent plastic part 1 in the form of a rear window from being adversely affected. The electrically conductive structures 2 may also be designed for signal transmission, current conduction, or the like, or also preferably as solar cells. The latter embodiment offers the advantage that solar cells in the form of electrically conductive structures 2 may be printed on transparent plastic parts such as vehicular panes, for example, and the energy from the solar cells is supplied via additional electrically conductive structures 2 to a plug-in connection or an electronic device, so that, for example, a fan is driven by the solar energy for ventilating or cooling the interior of the vehicle at high temperatures. In addition to this ventilating function, solar cells in the form of electrically conductive structures 2 may also be printed on the transparent plastic part 1 to provide energy for other equipment.

The embodiments are only examples. A combination of these approaches, or also thermal pre- and post-treatment of the components, impossible as well. Therefore, the design is versatile.

List of Reference Numerals

1. Transparent plastic part

2. Conductive structures

3. Protective layer (film, silicon layer, or other)

4. Transparent plastic film

5. Joining material (adhesive, for example)

6. Injection-molded or insert-molded transparent plastic

7. Transparent plastic film

8. Protective layer

9. Transfer medium during the injection molding process

10. Transfer film

11. Transparent plastic part with conductive structures 

1. A transparent plastic part (1, 11) of an electrically nonconductive material on or in which electrically conductive structures (2) are integrated for use in a motor vehicle, characterized in that the electrically conductive structures (2) are printed on an outside surface.
 2. The transparent plastic part (1, 11) according to claim 1, characterized in that the electrical conductive structures (2) are imbedded.
 3. The transparent plastic part (1, 11) according to claim 1, characterized in that the electrically conductive structures (2) are imbedded by an additional layer (3, 8).
 4. The transparent plastic part (1, 11) according to claim 3, characterized in that the additional layer is a transparent foil (7).
 5. The transparent plastic part (1, 11) according to claim 3, characterized in that the additional layer is an antiscratch coating (3).
 6. The transparent plastic part (1, 11) according to claim 1, characterized in that the transparent plastic part is a finished part made by injection molding and sheet assembly.
 7. The transparent plastic part (1, 11) according to claim 1, characterized in that the transparent plastic part is an oversprayed transparent plastic sheet (6, 7).
 8. The transparent plastic part (1, 11) according to claim 1, characterized in that the transparent plastic part is a injection-molded sheet-assembled part assembled by gluing.
 9. The transparent plastic part (1, 11) according to claim 1, characterized in that the transparent plastic part is an externally finished injection-molded or sheet-assembled part.
 10. The transparent plastic part (1, 11) according to claim 1, characterized in that the conductive structures are integrated into the transparent plastic part by a transfer process (9).
 11. The transparent plastic part (1, 11) according to claim 1, characterized in that the transparent plastic part serves for glazing the vehicle, as for example the window or roof.
 12. The transparent plastic part (1, 11) according to claim 1, characterized in that the transparent plastic part is PC or PMMA.
 13. The transparent plastic part (1, 11) according to claim 1, characterized in that the electrically conducting structures are an antenna system, heater, or solar cell. 